Well... We did the Midsummer Dream Ride with the GPTR.
Fantastic single-track. First 35-40km's was all single track. Other than being mostly sand (and the requisite dust), it was quite good. Great place to ride if it is wet. If you don't like sand woops, don't ride in the Ganaraska! Most straight-sections of trail on the West side are riddled with them.
Afternoon after lunch in the East forest was the best. More elevation changes (although nothing like Calabogie.... think of a Limerick that is 4-5x larger with a bit more "hills") and better overall dirt/terrain. You can easily do 120km's of riding there in a day between East/West with only a few ATV trail traverses between sections.
GPTR was a great host. Only suggest is that they start planning/advertising it earlier! Only had 60 riders out and they needed ~100 to break even. I thought 60 was pretty good for a ride that only opened for Registration roughly a week before the event.
If you ever want to ride there, stay @ Sandaraska Park campground (
www.sandaraskapark.ca). There is a trail-head leading into the West forest right from the campground. They're horse/2-wheel friendly. They have a decent pool, showers/washrooms, stuff for the family and fully-serviced sites or tent camping. All the trails are family/small-wheel friendly.
Keep in mind the Ganny is a multi-use forest. So EXPECT to come across Horses, ATV's, etc. More-so on the West Side. I didn't see anyone (but other riders) on the East side.
Cheers,
G.